IGCSE Biology Paper-4: Specimen Questions with Answers 137 - 138 of 279

Glide to success with Doorsteptutor material for Bank-PO : get questions, notes, tests, video lectures and more- for all subjects of Bank-PO.

Question 137

Edit

Write in Short

Short Answer▾

Mammals also have a lymphatic system.

Outline the functions of the lymphatic system.

Explanation

The lymphatic system has three functions:

  • The removal of excess fluids from body tissues. This process is crucial because water, proteins, and other substances are continuously leaking out of tiny blood capillaries into the surrounding body tissues. If the lymphatic system didn՚t drain the excess fluid from the tissues, the lymph fluid would build up in the body՚s tissues, and they would swell.
  • Absorption of fatty acids and subsequent transport of fat, chyle, to the circulatory system.
  • Production of immune cells (such as lymphocytes, monocytes, and antibody producing cells called plasma cells) .

Passage

Cotton, Gossypium hirsutum, is grown for the fibers that form within the fruits after fertilization, as shown in Fig.

Fibers from the fruits of cotton plants are used in the textile industry.

The Fibres
  • Cotton plants have been genetically engineered to produce a protein that is toxic to the caterpillars of several insect pests. This gives the cotton plants resistance to the pests.
  • The cry gene for pest resistance was isolated from the bacterium Bacillus thuringiensis and inserted into the cells of cotton plants as shown in Fig.
Bacterial DNA

Question 138 (1 of 5 Based on Passage)

Edit

Write in Short

Short Answer▾

Outline the advantages to farmers of growing genetically engineered cotton plants that contain the toxic protein.

Explanation

  • It improves production and raise farmer՚s income. Farmers are still practicing traditional process of seeding and cultivation, which required scientific moves for raising their production. Hence, it is one of the moves to enhance the farm production.
  • It reduces the use of pesticide and insecticide during farming that might be great moves for the betterment of the food supply.
  • It can feed a rapidly increasing population because it shows dramatically increased yields.
  • It can produce more in small area of land.
  • BT cotton greatly reduced the use of toxic pesticides. BT cotton produces a common soil bacterium, Bacillus thuringiensis (BT) . It is a natural pest repelling bacterium that is toxic to many worms and pests that can harm the crop but is not hazardous to humans. BT is widely sprayed on crops by organic farmers as a pesticide.

Developed by: